A surgeon at UCLA Health has performed the world’s first successful bladder transplant, marking a breakthrough in transplant medicine that could transform treatment for patients with end-stage bladder disease. The procedure, completed in May 2025, combined a bladder and kidney transplant in a single operation—a technique that had never been attempted in humans before.
The success, detailed in a The Lancet paper published on June 23, follows years of research, including experiments with pigs and cadaver donors. At one point during the development phase, the team faced a critical moment at 2 a.m. when Dr. Nassiri had to manually flush a removed bladder with a specialized solution to preserve its blood supply—a step that had previously failed in earlier trials.
The lead surgeon, Nima Nassiri, MD, director of the UCLA Bladder Transplant Program, began exploring bladder transplantation during the COVID-19 pandemic. His team’s first human recipient was Oscar Larrainzar, a 43-year-old who had survived bladder cancer but lost bladder function. Larrainzar had already been part of Dr. Nassiri’s surgical team in 2020 when his failed kidneys were removed, establishing a long-standing connection before his eventual transplant. After years on dialysis, Larrainzar received both a new bladder and kidney in a single surgery. The operation worked immediately: he urinated on his own for the first time in seven years.
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“It has been beyond expectations,” Larrainzar said. “It’s like living a normal life again.”
The procedure’s success hinged on overcoming technical hurdles. Bladder transplants are far more complex than kidney transplants due to the organ’s delicate blood supply and the precision required to preserve it. Nassiri’s team had to develop new methods for flushing the bladder with a specialized solution to maintain circulation during removal—a step that had failed in earlier attempts. The vascular challenges of the pelvic region, combined with the need for meticulous surgical technique, made this a high-risk endeavor. Dr. Nassiri had previously worked with pigs and human organ donors in preparation, refining the process over years before attempting the first human transplant.
UCLA’s Unmatched Role in Pioneering Surgery
Regulatory approval for the trial took extensive coordination across review boards, organ procurement organizations, and UCLA’s Department of Urology. The hospital’s history in kidney transplantation, along with its culture of innovation, made it the only institution capable of attempting the surgery. OneLegacy, UCLA’s organ procurement partner, played a critical role in securing donor organs. Dr. Nassiri emphasized that the procedure could only have succeeded at UCLA due to the department’s long-standing expertise in kidney transplantation and its supportive environment for experimental therapies.
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Nassiri’s work didn’t begin with a goal of making history. He entered medicine to follow in his older brother’s footsteps, but his career took a different path after joining the David Geffen School of Medicine at UCLA. There, he trained under Jeffrey Veale, MD, a pioneer in “tolerance” kidney transplantation, a technique that could eliminate the need for lifelong immunosuppressive drugs. That experience shaped his approach to bladder transplants, particularly in his ambition to eventually combine the two procedures. Dr. Nassiri described his time at UCLA as a “transformational moment,” exposing him to the department’s reputation as a leader in urological innovation.
National Recognition and Expanding Trial
Since joining UCLA’s faculty in 2025, Nassiri has focused exclusively on bladder transplantation, supported by the department’s leadership. Mark Litwin, MD, then-chair of urology, called the work a “principal focus” of the program. The team’s success has drawn national attention, including recognition from TIME100 Health, which named Nassiri one of the top 100 individuals shaping the future of medicine. The achievement also garnered significant media coverage, further highlighting the potential of bladder transplantation as a new advance in organ replacement therapy.
The clinical trial now includes two additional bladder-kidney transplants. The ideal candidates are patients with end-stage bladder disease who already require or will need immunosuppression. The technique could also benefit children and adolescents, who often face kidney failure due to bladder dysfunction. Current treatments for pediatric patients, such as reconstructive surgery using bowel or intestine, carry lifelong complications, including chronic infections and metabolic issues. Dr. Nassiri noted that in children, bladder failure is a leading cause of kidney disease, making transplantation a critical unmet need.
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Vision for Drug-Free Transplants Ahead
Nassiri’s long-term vision combines bladder-kidney transplantation with Veale’s tolerance program. If successful, patients could receive both organs and avoid toxic anti-rejection drugs entirely. “My ideal situation would be this: There’s a patient who doesn’t have functional kidneys or a functional bladder, and we give him a kidney and we give him a bladder, and we take him off immunosuppression and he lives a normal life,” he said. The integration of these techniques remains a key focus of his research, with early experiments already underway to test feasibility.
For now, the procedure remains experimental. The team is training residents and fellows in the technique, with one trainee planning to bring it to a program in Canada. Nassiri’s work reflects a broader shift in transplant medicine: from treating symptoms to restoring function. The first successful bladder transplant isn’t just a medical milestone, it’s a proof of concept for a future where organ failure no longer means a lifetime of limitations. The procedure’s success has also inspired collaboration with other institutions, as surgeons worldwide begin exploring its potential applications.
